A polymer organic film may be used as an interlayer insulating film of LSI or the like or a liquid crystal alignment film, and has very excellent electrical, optical, and mechanical characteristics. In particular, since, for example, polyimide or the like has a high glass transition point and has excellent heat resistance, chemical stability, alignment control, and the like, polyimide or the like is used as a heat- and radiation-resistant material and a space-survival material, and is also being considered to be used as an insulating material of a superconducting magnet used in a fusion reactor, a protective material for preventing degradation of a material for machinery due to atomic oxygen in space, or the like.
As a method for obtaining such a polymer organic film, a conventional method of polymerizing a monomer by using a solvent to obtain a solution and coating the solution on a substrate is known. However, since the conventional method uses the solvent, impurity introduction or the like occurs and it is difficult to obtain a thin film having a uniform thickness less than 1000 Å. Also, as a method for obtaining a monomolecular layer film, manufacture of a thin film using a Langmuir-Blodgett (LB) method has been studied. However, since reactions, such as substitution of hydrophilic and hydrophobic groups and the like, are complicated and, it is difficult to control a surface pressure required when the thin film is obtained, it is difficult to obtain a thin film with a large area. Also, since a solvent is used during polymerization or the like, impurity introduction occurs as well.
Meanwhile, contrary to such a wet process, a deposition polymerization method (vacuum deposition polymerization method) for directly obtaining an organic film by vaporizing a material monomer in a vacuum bath and polymerizing the vaporized material monomer on a substrate has been suggested. Since this method is a dry process under a non-thermal equilibrium state, an organic film that may not be obtained in a conventional chemical wet process may be obtained. Since the material monomer is introduced into and adhered to a protrusion/recess portion of the substrate, this method may form a film with good coverage (Patent document 1).
(Patent document 1) Specification of Japanese Patent Publication No. 3758696
However, the deposition polymerization method introduces the material monomer into a film forming container in a state where the film forming container itself is heated to the same temperature as that at which the material monomer reacts in a gas state. Accordingly, a thermal polymerization reaction of the material monomer occurs not only on the substrate but also on a wall surface of the film forming container, and as a result, a desired organic film is formed not only on the substrate but also on the wall surface of the film forming container.
The organic film formed on the wall surface of the film forming container is detached from the wall surface to become particles, and the particles are mixed in the organic film formed on the substrate, thereby degrading a film quality and reducing a manufacturing yield. Also, since the thermal polymerization reaction occurs not only on the target substrate but also occurs on the wall surface of the film forming container, the use efficiency of the material monomer is reduced.